This invention relates to rapping systems for electrostatic precipitators and, more particularly, to a novel rapper control system and rapper assembly for electrostatic precipitators.
In a typical electrostatic precipitator assembly, particle laden gas is passed through a series of stages or fields of the precipitator and particles such as dust or ash are electrostatically attracted to precipitator plates. The gas becomes progressively cleaner as it passes through each stage until, at the output end of the precipitator, relatively clean gas is discharged.
As material such as ash accumulates on the plates and electrodes of the precipitator, there is a decrease in the collecting efficiency of the precipitator. Accordingly, rappers are typically employed to impart mechanical vibration to the plates and electrodes so that the accumulated material drops into a collection bin or hopper out of the gas flow path. Rapping is thus quite important to the continued efficient operation of electrostatic precipitators.
Numerous ways of controlling the rappers in a precipitator have been devised and include various mechanically and electrically actuated circuits. Typically, such circuits require extremely high voltage power supplies and/or energy storage means in order to provide the requisite electrical current to the rappers to generate the desired intensity of rapper impact. Moreover, various complicated and thus quite costly schemes of control have been devised to ensure rapping in the various precipitator stages or fields with the appropriate frequency. Such systems may, for example, be linked to some precipitator operating parameter such as sparking rate in order to provide the appropriate rapping frequencies for the various precipitator fields.
It is an object of the present invention to provide a novel rapper controller for selectively energizing rappers of an electrostatic precipitator assembly in a manner which overcomes these and other problems of prior art rapping systems.
It is another object of the present invention to provide a novel controller for selectively energizing rappers of an electrostatic precipitator from available a.c. line voltage.
It is a further object of the present invention to provide a novel controller for energizing rappers of an electrostatic precipitator from an a.c. supply through the application of a rectified d.c. potential to a rapper supply bus common to a plurality of rappers and through the selective connection of the rappers between the rapper supply bus and a common return bus over the time period during which the d.c. potential is supplied to the rapper supply bus.
It is yet another object of the present invention to provide a controller for selectively energizing rappers of an electrostatic precipitator assembly wherein the controller is electronically operated and comprised primarily of solid state devices.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from the following detailed description when read in conjunction with the appended drawings.